How to Mix Film Surround Sound Audio on A Budget

I used to think certain projects were off-limits for your typical home-studio freelancer.  I wrongly assumed that some projects could not be done by those that do not have the funds to afford costly equipment.

A friend of mine was on a tight deadline and needed a freshsurround-sound audio mix for his short film Kolory Listopada that would debut at the Festival du Novéau Cinema. I obliged,taking up the challenge of figuring out how I could do it without the equipment,forcing me to be creative and resourceful

I knew 3D audio could be simulated. In fact, I had a mind-blowing experience of an A/B comparison of 7.1 surround sound audio being played through a home theater setup, and then through DTS Xperi’s technology of simulating it through headphones (mimicking the existence of virtual sound sources).

What the hell does that mean?

Imagine you are a caveman 100,000 years ago. You hear a rustling in the bushes a few feet away and your survival depended on discerning the origin of that sound. In the off chance that it was a hungry saber-tooth tiger, it meant you knew which direction to run. Our brains have developed a finely tuned mechanism to understand how sonic waves interact with not only the shape of our ears, but with our shoulders, face, head, etc, before the sound finally reaches the inner ear. In mathematical terms, this is known as the head-related-transfer-function (HRTF).

In today’s age of AR/VR, simulating HRTF has been one of the greatest challenges. A few audio plugin companies such as Waves have used this concept to create innovative tools for musicians and engineers.

Now it is possible for a home-studio freelancer to mix in surround sound with just a pair of headphones. Using Ableton Live 10, the Soundflower virtual audio interface, a plugin host (LiveProfessor 2) and the Waves NX Virtual Room plugin, I was able to do just this.

Here’s how it works:

  • Six output channels (L, C, R, LS, RS, LFE) were set up in Ableton Live using Soundflower 64ch as the audio out device.
  • These channels were then fed into a plugin host (LiveProfessor 2), which hosted the Waves NX Virtual Room and Izotope Insight (for metering).
  • NX Virtual room then mixes down to a 2ch stereo mix (i.e. your headphones) – All of the audio-processing to simulate the effects of HRTF and room ambience is taken care of. The Waves NX Virtual Room also tracks the orientation of your head, so that the positions of the virtual sound sources remain fixed.

Kolory Listopada successfully premiered at the 47th edition of Festival du Noveau Cinéma in Montreal earlier this month with fresh new sound design and surround-sound audio mixed by yours truly.

Keep your eyes peeled for the web release! And let me know if you’d like a more detailed tutorial on how to mix in surround-sound with headphones.

 – Kontejas

Building a Home Studio

Long gone are the days when musicians fight ferociously for professional studio recording time. And although there are many advantages of using a proper studio establishment, perhaps because of the aural fidelity of music software, digital audio workstations and hardware emulation nowadays, we see that more and more individuals are making use of their living spaces for creation.

So, what does your own home studio do? We do not need to keep in mind that every living space is ideal, and that at the end of it all, one makes the best of what is available. Now, there is plenty of information on the Internet about home studio configuration and it is quite overwhelming to sift through it all. So here, I will describe what I did with my space, in the hopes that it can provide some insight into the process.

I live in a single bedroom apartment, with many spatial constraints – furniture, windows, room shape, orientation, etc. However, with careful planning and research I was able to figure out an optimal setup and sound treatment for my room without too much reconfiguration.

First and foremost, one must understand the character of the room that is available to them – every room has a unique “acoustic personality”. I chose to use my living room as my creation space. It is a nearly square room that is 13’3 “x 14’6” with 12 foot ceilings, hardwood flooring and concrete walls. The living area joins with the kitchen area, so the length of the room is effectively extended beyond the aforementioned dimension.

To qualitatively describe the acoustics of this room: it has a very noticeable echo and reverberation, with a lot of treble “snap” – Not very favorable conditions for mixing music. Even with furniture in the room, there was still noticeable echo. So I had decided to take on the challenge of transforming this space into a decent “home studio”

I am a sucker for area rugs with intricate designs and patterns. After spending some time window-shopping, I finally bought a Persian design area rug off Amazon which not only makes my apartment look sexy, but also has some acoustic absorption characteristics as well.

Now that I had the aesthetic aspect of my apartment covered, time for the real deal … How does one approach the problem of acoustic treatment? Like I said, there is a plethora of information on the Internet about this subject. Here is one pretty comprehensive tutorial  which I used as a guideline.

Positioning the Sound Sources

First and foremost, positioning of the
sound-sources is key. Near field studio monitors like my KRK Rokit 5’s need to
be placed approximately 3 to 4 feet apart pointing to a listener who is the
same distance away from each monitor. In other words, the listener’s head and
the two monitors should form 3 vertices of an equilateral triangle as shown

Additionally each monitor was placed on a
stand and isolated from the stand surface with Lyx Acoustic Foam isolation

One must tackle the acoustic absorption
problem in order of precedence based on how different frequencies interact with
the room geometry. Bass frequencies are the most difficult to control. The low
end always loves to hang out and bounce around in the corners and edges of your room. Reflection
of bass frequencies in the corners of your room tends to cause a bass heavy
listener experience.

Image courtesy of

Therefore, the most important areas to cover
with absorption material in your room are the edges and corners. Bass traps are
the most effective way to fix this problem.

First, I attempted to take care of my
trihedral corners. I found these corner foam wedges approximately 1’x1’x1’ on
Amazon, so I went ahead and bought a 4-pack to place at each of the 4 top
corners of my room.

Next, the dihedral corners of the room needed large bass trap panels.

Building Bass Traps

Bass traps tend to be the most expensive ticket item for
building home studios. Thankfully there are hundreds of tutorials out there on
how to build your own with basic supplies from Home Depot or any hardware
store. The basic idea is to build a rigid frame filled with insulation material and
wrapped with breathable fabric in order to deaden the low frequency buildup in
the corners and edges of your room. So here is what you need:

  • Denim, Rockwool, or Fiberglass Insulation (if
    you use the latter two, make sure you      wear proper protective equipment)
  • Wood planks of the desired dimensions of your
    bass trap
  • Wood screws
  • Fleece fabric by the yard from a fabric store
  • Picture wire and hooks for hanging the bass trap

I constructed 5’ x 1.5’ frames out of the wooden planks.

The wooden frames were then laid out on a large sheet of
fleece fabric and the center was filled with the denim insulation.

Pulling the fleece fabric taut, I was able to wrap the frame
and insulation to form the large rectangular bass traps. The fabric was then
stapled to the frame. Using picture wire and threading loops I was able to hang
the bass traps on monkey hooks in the walls.

Now that the dihedral corners of the room were acoustically
treated, all that was left was installing mid-to-high frequency absorption
panels on the walls. I ordered a 48-pack of 1’x1’x2” foam squares off Amazon.
Two panels of 12 squares each were constructed to hang at the first reflection
of each monitor.

For additional absorption behind my monitors, I hung a large moving blanket against the wall.

Validating the Acoustic Treatment

Say we treat our room with the proper
equipment, padding, and absorption surfaces. How do we know whether it works?
In order to determine this I have taken various quantitative and qualitative
data. To do this, I played back various audio clips and placed a
large-diaphragm condenser mic at the position of the listen to record what was
played. Here are the measurements I took:

  • Ambient noise
  • Sine-wave sweep across 20Hz to
    20kHz and a spectral analysis
  • White noise (Gaussian and
  • Pink noise
  • Kick & Clap playback

Placing a mic at the position of the listener
allows us to capture each of these playback sounds from the monitors.

Right off the bat, we can already see,
qualitatively the vast improvement in sound before and after the acoustic
treatment. Have a listen…

But just to quantitatively prove how much of
an improvement this was to the acoustics of the room, I did some spectral and
temporal analysis of each of the measurements I took above.

Here are a few examples… The sine-wave sweep
as you can see below, was narrower in terms of frequency spread after
installing the acoustic treatment. This was probably due to fewer reflections
of the room walls and surfaces.

Listening to the kick sample above we hear a
prominent room reverberation before acoustic treatment. This is confirmed even
with spectral analysis of the samples, where we saw a longer decay on certain
frequencies on the kick before treatment and a narrower signal after.

Here is one more example of pink noise being
improved. Pink noise is a type of signal where each octave (frequency harmonic)
carries an equal amount of noise power. For more information on pink noise,
click here. We see more prominent and defined high frequency harmonics
after acoustic treatment. In other words, the signal-to-noise ratio is noticeably improved after treatment.

Final Thoughts…

This home studio is a work in progress. I still have excess acoustic foam squares and a frame for one more bass trap. I plan on putting a foam panel on the ceiling right above the listener’s head, and a bass trap behind my rig, along the room edge above the monitors. For now, I hope that this final picture captures the breadth of the transformation of my creative space. Not only is it acoustically pleasing, but aesthetically as well. More updates to come!